Not bad - in the 'does what it says on the tin' school. Did well for them.
Black type on a dark green background is not easy to read, try other lighter colours.
You might add an email contact form
You could add 'testimonials' from satisfied customers.
You do have an address on it don't you, not just a phone number.
Edit:
No - you do npot have an address. This is a turn off as it hints at avoidance of customer contact if things go wrong. Same applies to builders etc.